Explanation:
South of the large star-forming region known as the
Orion Nebula, lies bright blue reflection nebula
NGC 1999.
Also at the edge of the
Orion molecular
cloud complex some 1,500 light-years distant, NGC 1999's
illumination is provided by the
embedded variable star V380 Orionis.
The nebula is marked with a dark sideways T-shape near centre in this
broad
cosmic vista that spans over 10 light-years.
The dark shape was once assumed to be an obscuring dust cloud
seen in silhouette against the bright reflection nebula.
But recent
infrared images
indicate the shape is likely a hole blown through the nebula
itself by energetic young stars.
In fact,
this
region abounds with energetic young stars
producing jets and outflows that create luminous shock waves.
Catalogued as Herbig-Haro (HH) objects, named for astronomers
George Herbig and Guillermo Haro,
the shocks appear bright red in
this view that includes
HH1 and HH2 just below NGC 1999.
The stellar jets and
outflows push through the surrounding
material at speeds of hundreds of kilometres per second.